Backfiring out the exhaust, or thru the intake? How are you tune up parts looking? (plugs wires cap rotor)

 

to be honest - it sounds like its backfiring around the cat. I can't tell if its up front or out back.

the new TPS - allows me to drive it and shut it down and it'll restart - I guess the old one was bad.

I haven't changed the wires, or anything in the cap, since I've owned the truck the past 3 years. I guess I can look at those, too. I've never messed with a distributor cap before - and I don't have a timing light, so I didn't want to screw something up.

I actually ran by the parts store to grab a new cap and rotor. I'll try those tomorrow and report the findings. I still have this horrible feeling that its a crank sensor or a wiring harness - but hopefully its just the distributor/rotor.

would that cause my symptoms - backfire under acceleration? and it only backfires under 40 mph. It drives perfectly fine on the highway.

 

Do not need a timing light for these trucks. Ignition timing is controled by the ECM. Trying to adjust ignition timimng by loosening the distributor will only screwup the fuel sync, then you will need to dealer or someone with the proper equipment to reset it.

Dave

 

Yeah, I noticed that when I bought it. It looks pretty basic. Any tips for keeping the spiderweb of wires in order? Hopefully this fixes it, but I'm not too optimistic. lol. Its just one of those things I need to replace anyhow.

 

May want to get plugs as well.

There is a TSB in the FAQ/DIY section here for plug wire routing. Follow that.

 

cap and rotor replaced. helped - runs better and backfires less, but still backfires.

I also reset the PCM and cleaned the IAC.

 

Have a look at a couple of your plugs. (like, all of them. )

 

plugs next, then wires, then that damn crank sensor if i need it. if that doesnt fix it, maybe its time to finally trade the truck in. lol